1. How can existing customers be identified in terms of profitability? To accomplish this, firms need to do two things. First, they must align information databases around the customer, using CIFs, rather than around products as is the traditional approach. Instead of data files being organized by product, with customers listed several times if they buy several products (e.g., a bank customer might be listed in a checking-account file, a savings-account file, a home-loan file, etc.), the data files must be organized by customer, with the products and affiliated revenues stored by customer. Many firms, especially financial and business-to-business firms, have begun to store product revenues by customer and are therefore able to examine customer tiers as described in the examples above. The second necessity is to understand, to record, and to store the costs associated with each customer in their customer files, a daunting task for service firms. While the accounting approach of activity-based costing (ABC) is useful, in many cases the allocation of service costs to customers is arbitrary at best. Ultimately, it is necessary that the management information system include a summary profitability figure for each customer that can be accessed easily. This is the number that is used to construct the customer tiers and that will be a guide as to how to best manage the customer relationship with each customer (see Zeithaml et al. 1999 for more details).